Bonneville America Forums Forums Technical Forums Performance Mods Carb Adjustment-scarry thought...

I read Dinqua's site regarding replacing the main jets with 130's. I ordered them and am looking forward to installing soon. I'm a bit nervous about taking the carbs off the bike, replacing the jets and re-assembling, but I'll get over it I guess once I start and have a home brew or two.

Now the question is, do I need to reset the adjustments? I see people list 3 and 3/4 out...on their descriptions...If I change the jets to 130, will I need to re-set the adjustments? On Dinqua's site, it looks like the adjustments are done with the carbs out, this was for the pilot jet adjustments, but this is not the same as the air/fuel mixture adjustment on the mains, right?

I guess I could use some help here before I screw it all up.

Do I also need a Carb Tuner to complete this project?
Idle is normal set at 850-1000?
If it is just the mains, and I drill out the airbox and use the Uni, will there be a need to make these adjustments?
And with one baffle out, how will this affect the air/fuel mixture as well?

Yikes, even these questions are making me nervous.

Charlie Thanks!

Piece of cake!!!
Check your tools first as I had to "modify" a few of mine.
A bench grinder close was a must for me.

I just did the 04 America jet change with out removing the
carbs. It's a bit tricky if you do not have the tools
or ever worked on something like this.

Take your time, don't get frustrated, and ask for help
if you need it. I did the BA and the SM in just under
2 hours. Course you have to consider brew timing,
rain showers and such into the 2 hours.

Dinquas instructions are very thorough. I printed them out to have on hand, and had no problems by following them to letter. The job looks tougher than it is until you get in there with the wrenches, then it all makes sense. The toughest part for me was getting my hand and the allen wrench in between the tire and the fender to loosen then tighten the airbox screws, but it was no big deal.

Take your time, and you'll do fine.




"Do I also need a Carb Tuner to complete this project?"

If you remove the AI, (which is a good idea) the left side is going to have much more draw than the right. A method to balance the carbs is advisable. Some have used home made balancers with great success.


"Idle is normal set at 850-1000?"

I prefer around 1000, for when the bike is a bit cold, it stays running better at 1000 at stop lights.


"If it is just the mains, and I drill out the airbox and use the Uni, will there be a need to make these adjustments?
And with one baffle out, how will this affect the air/fuel mixture as well?"

See Pat's jetting calculator for advice. I'm thinking three turns out on the carb adjuster screws is a good place to start.

The carbs on my 05 Speedmaster can be adjusted while in place and mounted up. I sprung the $20 for the D tool.

The screws that hold the bowls in place apparently have offered issues to some folks. Mine felt glued in with Loctite, but if you remove the bowl screws while the carbs are off, you should have no problems removing them with a short stout screwdriver and a firm hand. A screw driver with a mashed and wrung tip may offer problems. I used a flea market cheapo screw driver, but the tip was in good shape.

Only one baffle out doesn't have much if any effect on performance and you definitely would not have to re-jet just for that. I didn't see much improvement til I took out 3rd baffle. I don't have my manual with me, but it says idle speed something like 50 rpm above or below 1000 rpm. 850 is probably too low.

The air mix screws can be easily adjusted at any time. While oyu have the carbs out, that is a good time to simply locate them, and maybe adjust them BOTH to the same spot as a starting point. You can tweak them later. Balancing the carbs is a good idea anytime to make a change, and something to do a couple times a year anyway. I have a tuner, so if you want to ride out to the island sometime, we can get you ballanced up in about 5 minutes.

It's better to use Pat's method the first time so you can break loose the bowl screws and see what you're doing. After that you'll be able chnage the jets without removing the carbs. I would invest in the D tool to adjust your air screws and get a carb tuner to sync your carbs.

Charlie,
If you're coming to the rally, hold off and we'll do them here for ya.
Also, it is far easier to get the allen screws that hold the airbox out if you lift the bike, remove the rear shocks at one end, and drop the rear wheel carefully and slowly. This gives you all the room you need. But you need to pull the pipes if they are in the way of the shocks dropping. Just take the bottom bolts off each shock and gently pry them off.

Thanks to all you guys. Knowing that I have support is helpful.

I think I was needing to re-jet as I am drilling out the airbox soon, and if I'm taking in more air, the need to more fuel makes sense. Another bit I read is that the bike comes tuned for EPA standards, not where is should or could be. So I presumed jets and more air, one less baffle, good idea, re-tuning, good too.

Pat, when and where is the rally? And I guess you mean balance the carbs while I'm there, not change the jets? Oooooh, mamma, how many beers would I need to buy to have a first hand lesson?

Charlie

So it IS possible to change the jets without removing the carbs? I'd be happier do try that since getting things back is always an issue for a newbie.

And, Pat, isn't it easier to empty the float bowls before you loosen the carbs? I do that everytime I store the bike for the winter.

Charlie

It is possible to change the jets without removing them, BUT the stock hardware stips very easily. If you get some hex head screws from newbonneville it will be much easier. Most people remove the carbs the first time, and replace the carbs with all the phillips head screws replaced with the hex head screws, then every other time you change jets you don't have to remove the carbs.

Yeah empty the floats for sure. You can re-jet without removing the carbs, but be VERY careful removing the float bowl screws. Replace them with allen head screws, and then be VERY carefull not to over-tighten them when putting them back because you'll scrip out the holes easily. The carbs are made from real soft metal.

You can remove stock phillips screws from bottom of carbs without stripping them. I used a small, ratchet bit holder with a new #2 phillips bit. You have to keep bit square with screw head, and hold it firmly engaged with other finger while turning. I did mine twice like that before I got my allen heads from Brent.

I had a hard time with a couple of the bowl screws and wound up having to use a needlenose vise grips to get them out. This would be next to impossible with the carbs in place. It isn't that hard to pull them. I'd say pull them the first time and install the allen screws in the bowls.

I agree with Rick. First time I had my carb bottoms apart was when I did the Freak so I had the carbs out. Brand new, old, it didn't matter what screwdriver I used, two of them would not come out. Stripped the crap out of them. Had to use needle-nose vice grips to crack them loose. Very glad I had the carbs loose. Made it a LOT easier.

Pull your carbs...

NorEast Rally

You are having a Rally?

I'd try removing the screws with the carbs in place first. If it works, you've saved some time and effort.
If not, well, you were headed that way in the first place.

Just be careful with the float, the hinge pin, and the float needle. They can all fall out, especially if you do this with the bike on the side stand.

Thanks Grump. I guess I'll try that first. I have a pebble driveway and will put down plywood for the jack, and drop cloths to locate all the dropped bits that always go to the ground and never are to be found. I ordered the hex screws from Brent and will try this all in a couple of weeks when the parts arrive.

Will the float, hinge pin and needle stay in place if the top of the carb is handled in any specific way?

I'm not sure I understand the question. The float hinges on a thin pin. When the bowl is full, the float holds the needle in its bore. When you drain the gas and remove the carb bowls, the float is free to hinge downward on the pin, allowing the needle to come out. The metal hinge pin can also slide out the side and let the float drop out of place.
It's no big deal - everything just fits back where it was, I was just letting you know so you don't LOSE any pieces....

(Photo courtesy of Pat's carb site)

By the book, warm idle is 1000 +/- 50.

The idle mixture is affected by the pilot jets. Changing the mains won't make any noticable difference. BUT, the idle mix will need occasional fine tuning to allow for seasonal changes, traveling to a different altitude, etc.

I have had good results adjusting the mixture for best idle speed. As the engine speeds up during adjustment, slow it back down to keep it running only on the idle portd.

Anything that changes the amount of airflow is likely to change the mixture and require adjutment.

If you can, it's a good idea to get some kind of carb balancing guage. Even if you don't change anything, this will drift over time.

Grump: I didn't understand the question either, but as you say, it all fits back together. I guess I'll see it once I open it all up. I'm a visual guy, can't follow directions, use a Mac. I'll get it.

Grey:Ordered the carbtune II 2 column. Waiting for it's arrival. Thanks Guys.

It is easy work on the bike if you've done bikes before.
Take it slow, handle the situation.
DO NOT use lock tite when you put it back together!
Simple lock washers are enuff! This ain't a HD!
(I Love Ya Kevin for sellin me the SM but I could
kick your a** up and down my yard for lock titen'
the dang float bowls! )

Loc-tite on float bowls..... brrrrrrr! Gives me the fitzwillies just thinking about it...

Did the carb thing as per Dinqua's outstanding guidelines. No problem, had time for a couple of brews while contemplating my next project. You know how it is, need to fix something even if it ain't broke. Am leaving the air box pretty much intack except for shortening the snorkel. Seems to run fine. Still messing with mixture but will eventually get it right. Has anyone tried this colortune thing ? Looks interesting, being able to actually see your plugs firing and adjust accordingly.

They do work pretty good. One of the guys here let me borrow his kit and I was able to get very close to where I am now with it. I cannot remember who it was (about 1.5 years ago)